Abstract

Europium thenoyltrifluoroacentonate (EuTFC) has an optical luminescence line at 612 nm, whose activation efficiency decreases strongly with temperature. If a sample coated with a thin film of this material is micro-imaged, the 612 nm luminescent response intensity may be converted into a direct map of sample surface temperature.

The authors report the crystal structure at 1 {angstrom} resolution of europium bound to diethylenetriaminepentaacetate covalently coupled to an organic chromophore, carbostyril 124 (DTPA-cs124; carbostyril 124 = 7-amino-4-methyl-2(1H)-quinolinone). The complex is highly luminescent in solution and in the crystal form. The Eu-DTPA-cs124 crystallizes in the space group C2/c with two molecules in the asymmetric unit. The two molecules form a dimer which is stabilized by {pi}-stacking of two carbostyrils and by the ligation of the carbonyl oxygen of one cs124 to the europium of the second half of the dimer. The ligation removes the last water bound to the lanthanide.more » The crystal structure also shows the amide oxygen between the cs124 and the DTPA is ligated to the metal. Spectroscopic measurements of the europium luminescence in the crystal show that 66% of the luminescence is centered around 617 nm with a full width at half-maximum of 2.5 nm. In solution, 48% of the europium luminescence intensity is in the 617 nm peak, with a fwhm of 3.5 nm. The europium lifetime in the crystal structure is 0.90 ms; the lifetime of the monomeric Eu-DTPA-cs124 is 0.62 ms in H{sub 2}O solution and 2.4 ms in D{sub 2}O solution. The differing lifetimes can be explained by the well-known effects of H{sub 2}O on nonradiative europium emission rates and by postulating an electric (crystal) field surrounding the Eu which is more anisotropic in the crystal than in the solution, creating a faster radiative rate of Eu excited state deactivation. This greater anisotropy is expected on the basis of the crystal structure. The crystal structure also suggests improvements in the linkage of cs124 to DTPA which may improve the energy transfer between the organic chromophore and the europium and sharpen the Eu emission spectrum in solution.« less

A luminescent temperature sensitive paint containing the molecule rhodamine B base (rhBb) is described whose emission intensity can be monitored by video camera to produce qualitative and quantitative two dimensional surface temperature maps. This paint was designed for use with the pressure sensitive paint containing platinum octaethylporphyrin (PtOEP), but is also a useful tool when used alone in the measurement of heat flow, boundary layer transition, and quantitative surface temperature during wind tunnel studies. The ability of the rhBb paint to produce a continuous temperature map makes it possible to locate structures in the temperature field on an airfoil thatmore » are otherwise undetected by surface mounted thermocouples spaced a finite distance apart. A dual temperature/pressure sensitive paint was investigated with both the rhBb and PtOEP dyes incorporated into the silicone polymer paint base of the pressure sensor. Photodegradation and batch variations in the polymer were found to compromise the calibration parameters of the PtOEP paint and therefore the accuracy of pressure predictions. Suggestions are made for improving the prediction ability of the paint. The molecule europium(III) thenoyltrifluoroacetonate (EuTTA) is also discussed as a temperature sensor for a two layer temperature/pressure paint. EuTTA can not be directly incorporated into the silicone paint base of the PtOEP paint (as the rhBp paint can), but performs well in non-oxygenpermeable coatings. Benefits of the EuTTA temperature paint include: (1) decreased photodegradation, (2) very bright luminescence intensity, and (3) long luminescent lifetime (several hundred microseconds). The long lifetime facilitates lifetime imaging, a technique currently under development as an alternative detection method where luminescent lifetimes rather than emission intensity are related to temperature and pressure.« less

We have synthesized and spectrally characterized a series of new luminescent lanthanide complexes based on linear and macrocycle polyaminocarboxylate chelates, covalently joined to an organic sensitizer 7-amino-4-methyl-2(1H)-quinolinone (carbostyril 124). These complexes are luminescent with both terbium and europium and have millisecond lifetime, sharply spiked emission spectra (<10 nm fwhm), large Stokes shifts (>150 nm), excellent solubility, moderate absorption (12000 M{sup -1} cm{sup -1} at 327 nm), and high quantum yields for lanthanide emission. These characteristics make them useful alternatives to radioactive probes, to fluorescent dyes, and as donors in energy transfer experiments. A comparison of luminescence, intensity, spectra, lifetime, andmore » number of coordinated waters is made. Net charge varies from -2 to neutral and water coordination number from 0.2 to 1.2. By comparison of lanthanide emission lifetimes with lanthanide chelates without sensitizer, it is shown that the sensitizer does not lead to nonradiative de-excitation and that the quantum yield for lanthanide emission is likely close to unity. These chelates are the most efficient energy transfer donors yet synthesized. In imaging, they may make possible two-color detection with no spectral overlap and a single excitation wavelength, as well as the ability to discriminate against short-lived autofluorescence background. 42 refs., 3 figs., 2 tabs.« less